Super Magnetic Storms: Past and Future. Bruce T. Tsurutani 1 and Gurbax Lakhina 2 1 Space Science Research Institute, Santa Monica, Calif. 2 Indian Institute of Geomagnetism, Navi Mumbai, India. The September 1, 1859 “Carrington” Solar Flare.
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Bruce T. Tsurutani1and Gurbax Lakhina2
1Space Science Research Institute, Santa Monica, Calif.
2Indian Institute of Geomagnetism, Navi Mumbai, India
Famous hand-drawing by R. Carrington: clearly what we now call an
“active region”. The AR caused multiple flaring and continuous geomagnetic activity
over a week duration.
“Description of a Singular Appearance seen in the Sun on September 1, 1859”
By R.C. Carrington, Esq.(MNRS, 20, 13, 1859)
“Mr.Carrington exhibited at the November meeting of the Society and pointed out that a moderate but very marked disturbance took place at about 11:20 am, September 1st, of short duration; and that towards four hours after midnight there commenced a great magnetic storm, ……….”
The CME took 17 hrs and 40 min to go from the Sun to Earth.
Carrington also gave us the average speed of the related CME/shock. Lord Kelvin was
convinced that there was no connection between solar and geomagnetic activity.
D.S. Kimball*(University of Alaska internal report), 1960
“Red glows were reported as visible from within 23° of the geomagnetic equator in both north and south hemispheres during the display of September 1-2”
*Kimball was a colleague of Sydney Chapman. He was not a permanent
employee of the University of Alaska, but came there for summers (from the east
coast) to enjoy the Alaskan weather (S.-I. Akasofu, personal comm., 2001).
*Measurements taken from a Grubb magnetometer. The magnetometer was “high
technology” at the time. The manual for calibration does not have a sketch of it (a copy of the
calibration information original can be found at the Royal Society, London).
Tsurutani et al. JGR, 2003
estimate the magnetic storm strength
From a plasmapause location of L=1.3 (auroral data: Kimball, 1960), we can estimate the magnetospheric electric field.
The electric potential (Volland, 1973; Stern, 1975; Nishida, 1978) for charged particles is:
Where r and Ψ are radial distance and azimuthal angle measured counterclockwise from solar direction
M dipole moment, q and μ- particle charge and magnetic moment.
The magnetospheric electric field is estimated to be ~20 mV/m. The interplanetary electric field has been estimated to have been 160 to 200 mV/m.
Tsurutani et al. JGR 2003
Dst is estimated to be ~ -1760 nT, consistent with the Colaba ~11 am response of ΔH = -1600 ± 10 nT.
The storm was the most intense in recorded history. Auroras were seen at Hawaii and Santiago, Chile (Kimball, 1960).
The Carrington storm was larger than anything that we have experienced in our lifetimes.
In comparison, the 1989 storm which knocked out the Hydro Quebec electrical grid had a Dst of “only” -589 nT.
Assume that a maximum CME speed at the Sun is 3,000 km/s.
Assume that the interplanetary deceleration is a minimum, 10%.
VS = ρ2/(ρ2 – ρ1) [V2 –V1]. n +V1(Rankine-Hugoniot)
Where 1 indicates upstream values (from the shock) and 2 indicates downstream values. n the shock normal. Here, the reference frame is the Earth.
The largest speed occurs for a perpendicular shock where the shock normal and all velocities are aligned (along the Sun-Earth line).
Vshock = 3480 km/s
MA = 63
MMS = 45
E = - (Vsw x B)/c
*derived from much lower MC fields and speeds
kρVSW2 = (2fB)2/8π (Sibeck et al. 1991)
where f2/k = 1.77 for low solar wind ram pressures and 2.25 for high solar wind ram pressures*.
Pdownstream = 244 nPa, an increase in pressure by ~240 times.
The magnetopause will be move inward to 5.0 Re.
*however none as high as assumed here.
*Again, the empirical relationship did not have extreme events like this included.
*Important for calculating magnetospheric relativistic electron acceleration
and formation of a new radiation belt (> 15 MeV).
Again, multiple shock event
Tsurutani et al., GRL 1992
How often can an event the size of the Carrington occur? Can one answer this by statistics? Our answer is no. (I can discuss this later with anyone interested)
Thank you for your attention.